Winterizing a house is a two-step process that includes sealing the many gaps and holes that allow heat to escape and upgrading insulation levels. The two work together to stop different types of heat loss.
Step One: Air Sealing
Heated air rises and looks for ways to escape through the top of the house. As it escapes, the pressure difference pulls outside air through cracks around windows, doors and other areas into the house. You can save energy by interrupting the cycle and attending to the escape routes in the attic.
To work in an attic, wear long pants, a long-sleeve shirt, gloves, safety glasses and a hat. Be sure to take a flashlight with you. Caution: Once in the attic, walk on the ceiling joists only. The spaces between the joists will not hold you, and you may fall through the ceiling. You can also create walkways by placing boards or sheets of thick plywood on the joists.
Plug Large Openings First
Sealing large openings will provide the biggest energy benefit. Make sure the attic hatch or attic door is not only insulated but also has foam weather-stripping around the edges. Other areas to check include:
- Dropped soffits. Soffits are often found in kitchens and bathrooms to hide ducts or pipes. If they are installed under the attic, they are often left open. If the attic is insulated, the soffit may be covered with a fiberglass batt. However, the insulation does not prevent air movement. To seal the soffits, remove the insulation and cover the opening with a sheet of rigid insulation board. Seal the edges with caulk and reapply the insulation.
- Flues, chimney and pipe openings. There is usually a space around any type of pipe or chimney that comes through the floor of the attic. Seal the opening around masonry chimneys or metal flues from furnaces with aluminum flashing and high-temperature silicone caulk. Seal around plumbing pipes using caulk or expanding foam. Be sure the sealant you use is made for the material it will come in contact with.
- Recessed lights. These fixtures provide a path for air and in some cases moisture if they are installed in a kitchen or bathroom under an attic. Standard recessed fixtures are difficult to seal, and doing it wrong can be dangerous. One solution is to replace the fixtures with Insulation Contact Air Tight (ICAT) fixtures. Unlike standard fixtures, these can safely be covered with insulation in the attic and are airtight.
Plug Small Openings
Apply caulk around electrical junction boxes that go through the attic floor. Once the attic is sealed, make sure windows and doors throughout the house are caulked and weather-stripped. If you have an unfinished basement, use caulk or expanding foam to seal where the house framing meets the concrete or block foundation. Seal around any pipes or wiring that goes through the basement ceiling to the floor above.
Step Two: Upgrade Your Insulation
Most attics contain some insulation. But there is a good chance that the insulation that is there does not meet current R-value recommendations. If you can see the tops of the ceiling joist, you need to add insulation. You can find the current recommendations here.
If you install fiberglass batts, place unfaced batts perpendicular to the joists to reduce heat loss through the joist. If you opt for loose-fill insulation, it is best to have a contractor apply the material because installation requires special equipment. The depth of the final application should be even throughout the attic.
No matter what type of insulation you install, be sure to keep it at least three inches away from recessed can lights if they are not rated for insulation contact. If there are soffit vents, install insulation baffles between the rafters. These provide a path for fresh air into the attic above the insulation. When used in combination with ridge or gable vents, they help exhaust moisture-laden air and ventilate the attic.
Fran Donegan is a DIY-for-the-home authority and writes on energy-saving tips for The Home Depot. Fran’s insulation tips are geared to provide you with numerous options for your home during the winter months.